1. Field of the Invention
This invention relates generally to water treatment and more particularly to a portable water treatment unit for purifying contaminated water.
2. Description of the Related Art
After a natural disaster has disrupted, severely damaged, or destroyed the physical infrastructure of a village or town, waterborne diseases often present the greatest risk to human health. This happens in both developed and developing world settings. Water supplies in these situations may be biologically contaminated by sewage effluents that mix with floodwaters, or physically contaminated with mud and soil that enter the water supply and hinder disinfection efforts. Harmful chemicals (e.g., nitrates and pesticides) are also typically found in flood water under such conditions, in addition to waterborne pathogens.
Contaminated water may be characterized as having a xe2x80x9cbiological loadxe2x80x9d and a xe2x80x9cphysical load.xe2x80x9d The biological load of the water refers to the level of biological contaminants in the water. The physical load of the water refers to the total level of suspended solids, dissolved solids, organic carbon, and turbidity in the water.
It is sometimes desirable to disinfect contaminated water for drinking and other uses. For example, after a natural disaster a region""s water supply may be compromised, necessitating emergency water treatment. It has long been known to disinfect water by exposing it to ultraviolet (xe2x80x9cUVxe2x80x9d) light, which kills contaminants in the water. In fact, disinfection devices that utilize UV light for purifying water have been used since the early 1900""s. Typically, the xe2x80x9cUV light disinfection unitxe2x80x9d or device is configured to receive a stream of water. The device normally includes a UV light exposure chamber, through which the stream flows and is purified by exposure to a UV lamp. One particularly effective UV light disinfection device is described in U.S. Pat. No. 5,780,860 to Gadgil et al. (hereinafter xe2x80x9cGadgil ""860xe2x80x9d), which is hereby incorporated herein by reference, in its entirety. The Gadgil disinfection unit is herein referred to as the xe2x80x9cUV Waterworks(trademark) unit.xe2x80x9d
Most UV light disinfection devices are designed for purification of water having a relatively low physical load. In order to treat water having a larger physical load, some water treatment units combine the UV light disinfection device with one or more filters for removal of particles from the water. Unfortunately, the filters tend to clog over time, and must be replaced periodically.
Accordingly, it is a principle object and advantage of the present invention to provide an improved device for purifying water, especially in the aftermath of a natural disaster or broken water main that has compromised a region""s water supply. Another object is to provide a device for emergency on-site treatment of contaminated water.
In particular, one aspect of the invention provides a portable water treatment unit that purifies contaminated water so that it is safe for drinking and other uses. In a preferred embodiment, the treatment unit weighs less than 100 kg (220 lbs) and occupies a volume of no more than approximately one cubic meter (30 cubic feet).
According to one aspect of the invention, biological and physical contaminants are efficiently removed from water by an appropriate combination of solid separators, filters, and UV disinfection. A solid separator, such as a hydrocyclone, removes larger particles from the water, such as silt and sand. The filters generally remove smaller particles. The use of the solid separator(s) reduces the tendency of the filters to become clogged. Advantageously, filter replacements are reduced by 20-80%. A pump is preferably included to help force the water to flow through the solid separator and filters. Preferably, a UV light disinfection unit, such as the UV Waterworks(trademark) unit, is provided downstream of the filters. For ease of transportation, some or all of the treatment unit components may be provided in or on a cart with wheels.
In one aspect, the present invention provides a water purification system configured to purify water, comprising an inlet configured to receive water, a solid separator, one or more filters, and an ultraviolet light disinfection unit. The solid separator is connected so as to receive water that has flown into the system through the inlet. The solid separator is configured to separate solids from water flowing through the solid separator. The one or more filters are connected in series, the filters being connected so as to receive water that has flown through the solid separator. The ultraviolet light disinfection unit is connected so as to receive water that has flown through the one or more filters. The ultraviolet light disinfection unit is configured to treat water flowing therein by irradiating the water with ultraviolet light.
In another aspect, the present invention provides a water treatment unit configured to purify water, comprising an inlet configured to receive water, a solid separator, and an ultraviolet light disinfection unit. The solid separator is connected so as to receive water that has flown into the treatment unit through the inlet. The solid separator is configured to separate solids from water flowing through the solid separator. The ultraviolet light disinfection unit is connected so as to receive water that has flown through the solid separator. The ultraviolet light disinfection unit is configured to treat the water by emitting ultraviolet light through the flowing water. The water treatment unit weighs 100 kg or less.
In yet another aspect, the present invention provides a method of purifying water, comprising the following: A flow of water is provided. The flow of water is directed through a solid separator configured to separate solids from the flow of water. The flow of water is directed through a series of one or more filters connected in series, the filters being arranged from coarsest to finest. The flow of water is directed through a UV disinfector configured to emit UV light onto the flow of water.
Despite its small size and weight, giving the unit the advantage of portability, the illustrated unit has the capacity to produce up to 15 L/min of drinking water from highly turbid and contaminated challenge water, enough to fill the needs of about 1000 people. At the same time, the unit is capable of reducing total coliform concentrations of 100,000-1,000,000 colony forming units (CFUs) per 100 ml to less than 1 CFU per 100 ml.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.